It’s been a turbulent ride, but the group is back. "We are the kind of people who don’t all belong in the same band together,' says Lindsey Buckingham.

It’s been 39 years since Lindsey Buckingham and his then-girlfriend, Stevie Nicks, joined Mick Fleetwood and John and Christine McVie in Fleetwood Mac.

Faster than you can say “Landslide,” the 8-year-old English blues-rock band and its two new American members shifted gears, changed musical styles and soared to international pop stardom. The 1975 album “Fleetwood Mac” was the group’s first release to top the U.S. charts, while its 1977 masterpiece “Rumours” has now sold more than 40 million copies worldwide and yielded such enduring hits as “Don’t Stop” and “Go Your Own Way.”

Did Buckingham ever imagine then that the band would still be active in 2013 and embarked on a world tour, which includes a Friday stop here at San Diego State University’s Viejas Arena?

“Well, time kind of slips by and it doesn’t seem that long,” said the veteran guitarist and singer-songwriter, speaking from a recent tour stop in Boston. “You know, when you’re in your 20s and contemplating that (long an) amount of time, you think: ‘Gee, will I even still be alive by then?’ So, it’s all kind of relative to your perspective. And it certainly is a surprise, although there are bands that have managed to stick around that long.

“The one thing that probably would have disabused me from thinking then that we’d still be around now is that the chemistry was always so volatile. Not just because there were two couples in Fleetwood Mac who had broken up (before ‘Rumours’ was completed), and that whole subtext, but from the point of view that we are the kind of people who don’t all belong in the same band together.”

Those two couples were, of course, Buckingham and Nicks, who split up while making “Rumours,” and the McVies, who separated before recording sessions for “Rumours” began and soon divorced. For any other band, such upheaval would spell the end. For Fleetwood Mac, it was the launchpad to fame, fortune and more upheaval, including drugs, Fleetwood’s bankruptcy, his on-tour affair with Nicks and enough other ups and downs to fuel a rock ’n’ roll soap opera.

“The conception is the volatility would eventually become a divisive force,” Buckingham said. “But I guess it went the other way; that same dynamic has a musical synergy, and we’re still working through things on a personal level.”

He laughed.

"There's no way (39 years ago) I thought we'd still be doing this, now, in this form."

Of course, Fleetwood Mac has hardly remained constant since its “Rumours” heyday.

Buckingham, always the most musically adventurous of the band, quit in 1987. He was replaced by Billy Burnette and Rick Vito. Nicks and Christine McVie left the group in 1990, followed by Vito a year later, at which point Fleetwood Mac ground to a halt.

In 1993, Buckingham, Nicks, Fleetwood and the McVies reunited to perform at newly elected President Bill Clinton’s inaugural ball (“Don’t Stop” was his campaign theme song). Burnette quit the same year, leaving Fleetwood and the McVies to soldier on. They were soon joined by singer Bekka Bramlett and, briefly, ex-Traffic singer-guitarist Dave Mason. Burnette returned in 1994 and Christine McVie left.

In 1998, a year after the band’s “Rumours” lineup reunited — perhaps as much for financial reasons as artistic ones — Fleetwood Mac was inducted into the Rock and Roll Hall of Fame. Christine McVie quit the band, for good, the same year.

“The Fleetwood Mac world certainly can be dysfunctional at times,” drummer Fleetwood said in a 2003 U-T San Diego interview.

Ironically, that very dysfunction seems to have sparked some of the band’s best work.

Witness "Rumours," a classic album born of failed relationships and the subsequent hostility between four of Fleetwood Mac's five members. That dysfunction, while personally painful, provided the essential artistic fuel. Rather than throw in the towel because their lives were falling apart, the band embraced that dysfunction -- or at least decided to not let it do them in -- as they made the album that would make them rock legends.

“Yeah, it’s very difficult to separate one from the other,” agreed Buckingham, who guests on the new Nine Inch Nails album.

"You have to start with the unique circumstances: John and Christine were married, and were in the process of ending their marriage, when Stevie and I joined the band. Stevie and I had our problems before then. And, to some degree, she and Christine egged each other on in dislodging themselves from their respective partners. So you had this unique dynamic going on within the band, and it really didn’t play out its conclusion until 'Rumours,' when John and Christine were completely separated and Stevie and I separated for good, right at the outset of (recording) that album.

"So, yes, the idea that you had to get on with what it was we went along to accomplish – or, if you want to call it, fulfilling our destiny – in order to do that, there needed to be a lot of compartmentalizing of emotions. There's a subtext, within that dysfunction, of heroism to rise above the more petty concerns and look at the bigger picture. And, in many ways, that became not just a musical soap opera, but that subtext of courage became the appeal of the album.

"Because, at some point, the album's success became about the success. But, also, it was just one of those weird situations where (listeners) were all sort of invested in this back story that was gong on. So it is very difficult not to factor that in, not just on a musical level, but in how it formed the identity of the album."

Adding another element to the album is that Buckingham and Nicks came from a completely different cultural background than Fleetwood Mac's three English members.

"Lindsey and Stevie were two California hippies, while the rest of the band were all hardcore Brits," recalled Ken Caillat, who co-produced "Rumours" and several subsequent albums for the band. "They used to kid each other that. The basic difference was the Brits in the group liked to drink and the hippies liked to smoke pot.

"Lindsey was the young musical genius, so to speak. He was always trying to stretch for higher goals. As the music developed, Lindsey was the guy adding a lot of colors."

Buckingham was also the guy who decided to replace McVie's bass parts on the song "Second Hand News," in addition to sitting down at Fleetwood's drum kit to show him he thought the drum part should go. It was a gutsy move for a new member of the band, but Buckingham doesn't see it that way.

"No, not at all," he said. "It was exactly what was needed. Going into Fleetwood Mac, there were certain things I had to give up, a certain part of the lexicon I had as a guitar player, in order to pare down and adapt to the existing sound. There were things that had to be adapted; it was a lesson in adaptation. But, at the same time, it was very clear to me that if this was going to work we had to cut through the b.s. and concentrate on what the needs of the songs were.

"I'm sure there were times when that particular contribution of mine might have made someone else feel like I was stepping on somebody's toes. Perhaps that was the case with John, but Mick never had a problem with the direction I was giving. Sometimes, he had a problem implementing it, but never on an ethical level.

"That (creative input) was something they were crying out for, in my mind. Much of what had been missing since (guitarist and band co-founder) Peter Green left the band (in 1970) was that kind of clear vision. And, right away, even in rehearsals, it was clear to me I had something to offer Christine, in terms of structuring her songs. And she recognized that. I think they all recognized that, on some level."

In a 2002 U-T San Diego interview, Nicks blamed Buckingham for the band having later imploded.

"Fleetwood Mac never would have broken up if it had been up to me, Mick John or Christine," Nicks charged. "So this is all Lindsey's ballpark. Lindsey either wants to be in Fleetwood Mac, or he doesn't..."

Does this make Buckingham the equivalent of Neil Young in Crosby, Stills, Nash & Young, a band that tours only when Young wants?

"I don't think it's quite that simple," he said. "Certainly, I have dictated terms at various times. I even left the band in 1987, because things had gotten out of hand, in terms of it being a functional organization. And I needed to get my feet back on the ground. Yes, there have been plenty of times where I've been the one, who dictated terms. But Stevie does that as well. So it's little bit more two-sided at this point. But, sure, any comparison you want to make to Neil Young, I'll take."

So, how are he and Nicks getting along now?

“In 2003 and 2004, there was a tangible polarity between Stevie and me,” Buckingham replied. “By our 2009 tour, that polarity had neutralized. … Now, on this tour, it seems to have swung the other way, to where Stevie and I are sort of playing out these (star-crossed lovers) roles, although it isn’t the reality of our lives! But it was, once, and slowly evolved into these roles.

"I mean, my God, I have three children and a beautiful wife, and that’s my reality. But the dynamic between Stevie and myself onstage this time is more of a love fest. And, for whatever reason, we are able to acknowledge that offstage and manifest it a little on stage. It seems to be playing out like we’re taking stock of that ‘What’s it all about, Alfie?’ moment. And that’s really very touching, and quite intriguing, to do with someone I’ve known since high school.”